Mowing machine



March 28, 1944. J, 5 CURTIS MOWING MACHINE Filed Dec. 31, 1941 NN #N W N IlmFNwhm Q n O .\NO Il Q -m l ur-.. I nlfl... Illwh S N .lm v.

Patented Mar. 28, 19 i4 l.

MowrNG MACHINE John S. Curtis, Tulare, Calif. Application neeember 31, 1941, serial Ne. 425,069

(ci. 'r4-5o) 3 Claims.

This invention relates to a mechanical device for converting rotary motion into reciprocatory motion, and more particularly to a device for converting the rotary motion of a. drive shaft into the reciprocatory motion of the cutting knife of 4 a mower. i

'I'he drive for the knife of a conventional mowing machine usually consists of a pitman driven from a crank provided at one end of a driving shaft. A fly wheel is commonly provided on the shaft and this fly wheel may be counter-bal-y anced in an attempt to compensate for the vibration due to the reciprocation of the knife. However such an `unbalanced rotary motion does not adequately compensate the unbalanced reciprocatory motion.'

It is among the objects of the present invention to provide a drive for a mower knife or analogous reciprocating member which drive shall adequately counteract the vibration due to theL reciprocation of the knife.

A further difficulty arising in connection with mowing machines as at present constructed resides in thefact that the pitman box requires frequent oiling. This means that the machine must lie/stopped and time lost to provide for such lubrication which if neglected results in the wearing or burning out of the pitman box, broken y* pitman sticks and other difficulties.

It is among the objects of the present inven-- tion to provide a drive for a mowing machine knife which drive is completely enclosed in an adequate housing so that the moving parts may be completely immersed in lubricating oil.

It is a further object to provide such an enclosed housing for the drive mechanism which housing may rotate about the axis of the driving shaft as the knife blade is lifted into an upright or non-cutting position.

It is a further object of invention to provide a drive mechanism of the type described which is entirely sealed against the entrance of dust or abrasives.

It is a further object of the invention to provide an improved driving mechanism for the knife of a mowing machine which mechanism will eliminate the necessity for the troublesome knife head of conventional machines and which accordingly will eliminate the necessity for the knife head wear plates.

The above and other objects and features of the invention will be obvious to those skilled in the art from a consideration of the following detailed description taken in conjunction with the accompanying drawing in which:

Figure 1 represents a horizontal section, with parts shown in elevation, through a drive mechanism constructed in accordance with the invention and also showing its mode of attachment to the mowing machine and its mode of attachment to the knife of the mower.

Figure 2 represents a vertical section through the driving mechanism taken upon the line-2 2 of Figure 1.

Figure 3 represents a. section taken upon line y 3-3 of Figure 2.

Referring tothe drawing reference numeral I0 indicates a fluid tight housing of a generally square or rectangular cross section. The housing I0 is supported by brackets II, which are' attached to the mowing machine in any suitable manner, thev housing Illy being provided with a raised portion or boss I2 projecting from one face thereof and an annular boss I3 projecting from the opposite face, which bosses provide pivots for the houseing I0 in the brackets II. A power shaft I4 which is driven from the mower in any suitable'manner extends into the housing I0 through` the boss I3 making an oil tight joint therewith and passing through the housing is journaled at its opposite end in the boss I2. Within the housing I0, the power shaft I4 carries a pair of steel cams or eccentrics I5 and I6, which eccentrics are rigidly fixed to the shaft and so mounted that the eccentricity of one is opposite to that of the other. 'I'he steel cams'or eccentrics I5 and I8 are provided with bronze driving blocks II and I8 which driving blocks provide a circular inner surface conforming to the circumferential surface of the eccentrics and plane external edge surfaces conforming to the inner surfaces of rectangularA yokes I9 and 20. The yokes I9 and 20 have exterior surfaces corresponding in general to the interior surfaces of the wall of the housing I0 except that they are of less width than the internal width of these walls although of the same depth as the internal depth of the housing. As .shown the eccentrics I5 and I6 and the bronze driving blocks I1 and I8 are identical in size and shape. The yokes I9 and 20 however are not identical in size and weight since the yoke I9 consists entirely of a rectangular frame while the yoke 20 includes a rectangular frame portion 2| which of itself is identical with the frame of yoke I9, but the yoke 20 also includes a heavy metallic block portion 22. A guide rod 23 is attached to the yoke I9 and projects into a cylindrical extension 24 formed on the side wall of the housing I0 to provide a rigid guiding surface for the rod 23. On

its opposite edge, and near a lower portion thereof, the yoke I9 is attached to a rod 25 which rod projects through an annular boss 28 formed on the lower side wall of the housing I0. Rod 2l is directly connected to the blade or knife 21 of the mower.

The yoke 20 is provided with guide rods 28 and 28 which project from the side walls thereof into cylindrical extensions 30 and 3l formed on the side walls of the housing I0 and which cylindrical extensions provide guide surfaces for the guide rods in the same manner as was previously noted in connection with guide rod 23 and cylindrical extension 2l.

In operation rotation'of the shaft Il rotates the eccentric I5 and this rotation 'of the eccentric moves the bronze driving block I1 up and down in the rectangular frame of the yoke Il while simultaneously moving the yoke I9 to and fro in the housing I0. This reciprocatory motion of theyoke I9 is directly transmitted to the knife rod 25 and thence to the knife of the mower. Simultaneously with this motion of the yoke I9 and the attached knife the eccentric I6 moves the driving block I8 in the opposite direction causing the block I8 `to move up and down within the frame 2I of the yoke 2li and thereby causing the yoke 20 to move to and' fro in housing I0 in a direction opposite to that of the motion of the yoke I9. The yoke 20 being heavier than the yoke I9 due to the heavy block portion 22 of the yoke 20 and the motion of this block 22 being in the opposite direction to the motion of the knife rod 25 may exactly compensate or counter balance the vibrations which would result from unbalanced reciprocating motion of the rod and the attached knife.

'I'he housing III may be supplied with lubricating oil through an opening 32 which opening is normally closed by a plug 33 so that suillcient oil may be contained in the housing to submerge or partially submerge the moving parts of the mechanism.

It will be -seen that when the blade is' elevated the entire housing Il may swing. in the brackets I I so that connection between the knife rod 25 and the knife 2l may be rigid.

It will also be apparent that since the raised portion or boss I2 and the annular boss I3 are v in alignment and have circumferential surfaces concentric with the surface of the drive shaft Il, the casing may/be rotated upon these two bosses which thereby serve as trunnions without affecting the connections with the drive shaft I4.

As disclosed packing glands are not provided to seal the clearance space between the drive shaft and the interior surface of the annular boss I3 nor between the reciprocating rod 25 and the interior surface of the annular boss 26. 'I'hese being the only two points at which lubrioating oil may leak from the housing the clearance between the rods and the interior walls of the boss may be such that oil of the usual viscosity of lubricating oil will not flow through this clearance or if desired a conventional packing gland may be used and in the following claims such expedients are intended to be included in the words oil tight nt.

While there has been herein described but a single embodiment of the invention other modiflcations and embodiments within the scope of the appended claims will be apparent to those skilled in the art.

Having thus described the invention I claim:

1. A drive for the knife of a mowing machine including in combination a driving shaft, a pair of cams mounted adjacently upon said shaft with the throw of one diametrically opposite Ato that of the other, a pair of yokes each of which is actuated by one of said cams, one of said yokes being directly connected to said knife to reciprocate the same and the other said yoke having sufiicient mass rigid therewith to compensate for vibrations due to the reciprocating motion of said knife blade in either direction.

2. A drive for the knife of a mowing machine including in combination a drive shaft, a pair of oppositely disposed eccentrics mounted adjacently on said shaft, a driving block mounted on each of said eccentrics and a yoke driven from each of said driving blocks, one of said'yokes being difrectly connected to said blade and the other of said yokes having sufficient mass incorporated therewith to compensate for vibrations due to the reciprocation of said blade in either direction.

3. A device of the class described comprising a housing, said housing having an opening in a side wall thereof, an annular boss surrounding said opening and projecting outwardly of said housing. a drive shaft extending through said opening and into said housing, a pair of oppositely disposed cams mounted upon said shaft within said housing, a pair of yokes each of which is actuated by one of said cams, a rod connected to one of said yokesl and projecting through an opening in an end wall of said housing, a member attached to said rod for reciprocation thereby, the other of said yokes having sufficient mass to compensate .for vibrations due u to the reciprocation of said member in either direction.

JOHN S. ('JUllt'IIS.` 

